Outdoor solar lamp

ABSTRACT

An outdoor solar lamp has a stand (10), with a foot (11), that supports a solar cell panel (12) in a housing (13). A passive infrared motion detector (14) is mounted in a peripheral surface of the housing (13). Incandescent lamps and a halogen lamp (not shown) are supported behind diffusers (15 and 16) respectively. The incandescent lamps operate automatically to be turned ON and OFF as required in a generally known manner. The halogen lamp is provided for security and is controlled to be turned ON when motion is sensed by the detector (14) to illuminate and indicate the presence of an intruder. A security mode of the halogen lamp is armed and disarmed remotely, using a handheld infrared transmitter.

The invention relates to outdoor solar lamps.

Solar lamps are already known which have a battery that is charged upduring daylight hours by solar radiation and which provide light atnight in gardens and open spaces when required. Generally, the lampoutput is of relative low intensity and incandescent lamps are used (seeU.S. Pat. No. 4,982,176). This may be quite satisfactory for normalillumination but when illumination output is required to besignificantly greater, for security purposes for example, the presentlyused lamps are not satisfactory.

It is an object of the invention to overcome or at least reduce thisproblem.

According to the invention there is provided an outdoor solar lamphaving a rechargeable battery, a solar panel, a halogen lamp, a lampdrive circuit, and a passive infra-red motion detector, in which thelamp is supplied with power via the drive circuit when the motiondetector is initiated.

The lamp may include one or more illuminating incandescent or lightemitting diode lamps and an automatic control circuit to supply powerfrom the battery to the lamps during at least part of each night.

Where two or more illuminating lamps are used they are preferablyelectrically connected in series, each lamp having a parallel circuitthrough which current can automatically pass if the lamp fails and goesopen-circuit.

The drive circuit may be arranged to supply automatically a low power tothe halogen lamp during at least part of each night such that thehalogen lamp glows to provide a relatively low intensity output.

The lamp preferably includes an arming and dis-arming circuit thatresponds to external stimuli, such as infra-red, ultrasonic or radiosignals.

An outdoor solar lamp according to the invention will now be describedby way of example with reference to the accompanying drawings in which:

FIG. 1 is an isometric view of the lamp;

FIG. 2 is a schematic diagram for the lamp; and

FIG. 3 is a circuit diagram for the lamp.

Referring to the drawings, in FIG. 1 the lamp comprises a stand 10having a pointed foot 11 that can be poked into the ground or otherwiseheld by grouting or the like in position. A solar cell panel 12 ismounted in a housing 13 at the top of the stand 10 and a passiveinfra-red detector 14 is mounted in a peripheral surface of the housing13. Circular protective light diffusers 15 and 16 are supported aboverespective shades 17 and 18 fitted to the stand 10. Three illuminatinglow intensity incandescent lamps and a halogen lamp, described below,are supported behind the diffusers 15 and 16 respectively. Lightemitting diode lamps with built-in diffusers may also be used instead ofthe incandescent lamps.

In normal use, the incandescent lamps are illuminated automaticallyduring at least some of each night by power derived from a battery (notshown) inside the housing 13 in a manner generally known already. Thehalogen lamp is however arranged to be illuminated whenever motion isdetected in a region adjacent the solar lamp by the detector 14 toprovide a comparatively bright illumination. This bright illumination isnormally or primarily used for security purposes to alert a householderof the proximate presence of a possibly unwelcome intruder. Theoperation of the detector 14 is controlled by an arming circuit, as willbe described below, so that the intruder detecting part of the lamp canbe remotely controlled, by selected infra-red signals for example.

In FIG. 2, the lamp includes a battery 19 and low battery voltagedetector circuit 20 connected to a logic and timing control circuit 21that controls the operation of incandescent lamps 22 and a halogen lamp23. The logic and timing control circuit 21 includes an infra-red sensor24 that responds to selected external infra-red signals and suppliessignals to the circuit 21 to arm and dis-arm the solar lamp, as will beexplained below. An ambient light intensity sensor 25 and a sensitivityand timing circuit 26 also supplies signals to the circuit 21. Thepassive infra-red detector 14 supplies signals via a passive infra-redamplifier 27 (which in practice consists of a preamplifier and anamplifier), which are monitored by the circuit 26, as seen later in FIG.3, for application via a comparator 27A to the circuit 21.

In operation, as will also be further explained below, the solar lamp isarranged so that during certain selected and relevant times, andaccording to the ambient light intensity, the battery 19 is charged upand the lamps 22 are turned ON and OFF automatically. Should the voltageof the battery 19 fall below a predetermined threshold, which isdetected by the circuit 20, the lamps 22 will be automatically turnedOFF, even during the night, to prevent damage to the battery 19 due tobeing otherwise discharged too much.

In FIG. 3, blocks are provided in dotted outline and numbered withnumerals which correspond to the components of FIG. 2 for ease ofreference. In addition, the circuit in FIG. 3 includes a chargingcircuit 28 including a diode 29 and zener diode 30 to allow the battery19 to be charged up from a separate mains supply. This may be neededinitially and from time to time during winter periods or during periodswhen the weather is poor. A power switch 31 is used to connect thebattery 19 to the rest of the circuit. The main switch 31 is normallyhidden or not immediately accessible from outside the housing 13 toprevent switching ON and OFF by an unauthorised person.

A lamp drive circuit 32 receives power from the battery 19, via theswitch 31, and supplies power separately to three incandescent lamps 22and to the halogen lamp 23. The circuit 32 also supplies power to theother circuits, via connection Vcc. The output voltage at Vcc isregulated by a blocking diode 33 and a filter comprising diodes 34 and35.

It will be noted that diodes 36 are connected in pairs in parallel witheach of the lamps 22. In practice, the overall voltage supplied acrossthe three lamps 22 is set at approximately 6 volts and the voltage dropacross each lamp is 1.5 volts. Each diode 36 will automatically conductcurrent if the applied voltage is above a threshold of 0.8 volts, thatis above 1.6 volts for each pair of diodes. This means that if any oneof the three incandescent lamps 22 fails, which normally means goingopen-circuit, the threshold voltage across the respective pair of diodesof that lamp will be exceeded and current will therefore then flow, viathe respective pair of diodes, to the other lamps. In other words, thedescribed diodes 36 enable the lamps 22 to remain ON even if one or twoof the three lamps fail.

The detector 24 is connected to a pin 38 of a micro-processor 39 in apart of the logic and timing circuit 21. The micro-processor 39 controlsthe operation of the halogen lamp 23. As such, the user of the solarlamp can control this operation using a suitable handheld infra-redtransmitter for example. The main purpose of the lamp 23 is for securityand so the lamp 23 is arranged to be turned ON in the presence of anybody movements in the region of the solar lamp. Use and the generalcharacteristics of infra-red motion sensors such as the detector 14incorporated in the solar lamp are generally known per se. In thisapplication, the user can however prepare the described circuit for theoperation of the halogen lamp 22, that is the user can "arm" the solarlamp (or circuit 21), by using a handheld transmitter. The solar lamp isalso arranged to be "dis-armed" using the same transmitter. The solarlamp can therefore be conveniently and remotely armed and dis-armed whenthe user is normally out of range of movement detection himself by thepassive infra-red detector 14. More importantly, any intruder is unableto dis-arm or turn off the solar lamp by operating the switch 31, orsome other manual switch on the solar lamp.

It is also possible to arrange for the lamps 23 to be remotelycontrolled by providing a second detector. The second detector respondsto infra-red signals at different frequencies to the signals used by thedetector 24 and the micro-processor 39. The second detector providesinput signals to a micro-processor 40 in a part of the circuit 21 thatcontrols the operation of the lamps 23.

A current damping resistor 41 and clamping diode 42 are provided toreduce any surges at turn ON of the halogen lamp 23 by the relay 43.

A manually operable mode selection switch 44 is also provided to set thetime period for which the halogen lamp 23 turns ON each time any motionis detected by the detector 14. Provision is made for time periods of 60seconds, 30 seconds and a test period of 10 seconds. The switch 44 mightbe used only during initial testing and assembly of the solar lampcircuit and then set, in the factory say, at either 60 seconds or 30seconds, as required.

An optional radio transmitter 45 is connected to a pin of themicro-processor 39. The transmitter 45 is turned ON automaticallywhenever the lamp 23 is turned ON. Typically, the transmitter produces ashort range transmission that can be picked by a nearby radio receiverin an adjacent house or building. Such a transmission will alert thehouse occupant, or trigger some overall security system for example,indicating that motion has been detected in the region of the solar lampwhich will normally need further investigation.

The halogen lamp 23 is capable of operating to provide a low intensitylight output, this is achieved by supplying power intermittently to thelamp 23, in a manner well-known in common dimmer supply circuitarrangements for example. As such the lamp 23 can be used in such a modeas an illuminating low intensity lamp in addition or as an alternativeto the lamps 22.

What is claimed is:
 1. An outdoor solar lamp comprising:a rechargeablebattery electrically connected to a solar panel; a lamp electricallyconnected to a lamp drive circuit; a passive infra-red motion detector,in which said lamp is supplied with power via said drive circuit whensaid motion detector is initiated, said lamp being a halogen lamp; oneor more illuminating lamps that are not initiated by said motiondetector; an automatic control circuit to supply power from said batteryto said illuminating lamps during at least part of each night whereinone or more of said illuminating lamps are light emitting diodes; andtwo or more of said illuminating lamps are electrically connected inseries, each said illuminating lamp having a parallel circuit throughwhich current can automatically pass if any of said illuminating lampsfail and go open circuit.
 2. An outdoor solar lamp comprising:arechargeable battery electrically connected to a solar panel; a lampelectrically connected to a lamp drive circuit; a passive infra-redmotion detector, in which said lamp is supplied with power via saiddrive circuit when said motion detector is initiated, said lamp being ahalogen lamp; one or more illuminating lamps that are not initiated bysaid motion detector; an automatic control circuit to supply power fromsaid battery to said illuminating lamps during at least part of eachnight wherein said illuminating lamps are incandescent lamps; and two ormore of said illuminating lamps are electrically connected in series,each said illuminating lamp having a parallel circuit through whichcurrent can automatically pass if any of said illuminating lamps failand go open circuit.